This invention relates to a water permeable artificial lawn and particularly to an artificial turf surface for playing fields.
As is well known a natural lawn which is intended to be used as a game or playing surface for "outdoor" sports presents various difficulties resulting from changing climatic conditions. Excessive dryness destroys the lawn's surface and makes its maintenance costly and complex. Excessive rain softens the grass surface and makes it unfit for play or causes its destruction when a game is played on it. Moreover, a natural lawn used by professional sport teams may be used for only a limited number of consecutive games in order to keep it in good condition. Even lawns on which few games are played under relatively favorable climatic conditions show uneven wear so that it must be periodically renewed from the bottom up. In order to remedy the aforedescribed problems various artificial types of lawns have been developed by which it should be theoretically possible to play in any season, independent of the weather, not only two or at the most three days a week but without interruption.
However, it is a disadvantage of the known artificial lawns as for example, those described in U.S. Pat. Nos. 3,332,828, German Published Application DOS 1,933,048, and German Utility Model Patent 6,914,675 that they cannot be played upon after a rain because the residual liquid is released too slowly and then not completely. This disadvantage is due to the fact that the fibers which form the pile of the lawn are held together by a very dense base fabric or by a non-porous layer applied to the entire surface of the back of base fabric. Such layers normally consist of synthetic material such as polyvinyl chloride or a rubberlike mass which, in either case, makes the lawn impermeable to water or makes the fabric entirely waterproof.
It has also been proposed, for example, in the German Published Application DOS 1,534,383 to make an artificial lawn water permeable by making the base fabric of otherwise impermeable materials which can be perforated during or after drying by means of needles of suitable thickness. In such artificial lawns, however, it is difficult to maintain a secure anchorage of pile fibers in spite of the perforation of the materials. On the other hand mere water permeability of the base fabric does not produce the desired release of the water unless a very highly water permeable layer is provided below the base fabric since the water would only enter the holes in the fabric but would not find its way out. This occurs, because the known base fabrics are completely flat on their underside and thus prevent water which had passed through the holes or openings of the base fabric to flow away.
It is the object of the present invention to provide an artificial lawn or turf overcoming the disadvantages of the prior art.
It is another object of the present invention to provide an artificial lawn wholly permeable to water while simultaneously insuring that the pile yarns forming the surface are firmly held in the base fabric.
It is another object of the present invention to provide an artificial lawn having a basic carrier which permits the safe release of the water from its underside.
It is another object of the present invention to provide an artificial lawn which may be easily installed and which may be maintained in proper stretched and playing condition.
It is another object of the present invention to provide an artificial lawn playable in all seasons.
These and other objects together with numerous advantages will be apparent from the following disclosure.